How Viruses Infect Specific Organs

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This illustration shows the plasma membrane of a T cell. C D 4 receptors extend from the membrane into the extracellular space. The H I V virus recognizes part of the C D 4 receptor and attaches to it.
HIV binds to the CD4 receptor, a glycoprotein on T cell surfaces. (credit: modification of work by NIH, NIAID)

Source: OpenStax Biology 2e

OpenStax Biology 2e

Glycoprotein and glycolipid patterns on the cells’ surfaces give many viruses an opportunity for infection. HIV and hepatitis viruses infect only specific organs or cells in the human body. HIV is able to penetrate the plasma membranes of a subtype of lymphocytes called T-helper cells, as well as some monocytes and central nervous system cells. The hepatitis virus attacks liver cells.

– What are chemical structures, composed of protein, that receive and transduce signals that may be integrated into biological systems?

These viruses are able to invade these cells, because the cells have binding sites on their surfaces that are specific to and compatible with certain viruses. Other recognition sites on the virus’s surface interact with the human immune system, prompting the body to produce antibodies. Antibodies are made in response to the antigens or proteins associated with invasive pathogens, or in response to foreign cells, such as might occur with an organ transplant. These same sites serve as places for antibodies to attach and either destroy or inhibit the virus’ activity. Unfortunately, these recognition sites on HIV change at a rapid rate because of mutations, making an effective vaccine against the virus very difficult, as the virus evolves and adapts. A person infected with HIV will quickly develop different populations, or variants, of the virus that differences in these recognition sites distinguish. This rapid change of surface markers decreases the effectiveness of the person’s immune system in attacking the virus, because the antibodies will not recognize the surface patterns’ new variations. In the case of HIV, the problem is compounded because the virus specifically infects and destroys cells involved in the immune response, further incapacitating the host.

– What is a biological preparation that provides active acquired immunity to a particular infectious disease, and typically contains an agent that resembles a disease-causing microorganism often made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins?

An oncolytic virus is a virus that preferentially infects and kills cancer cells. As the infected cancer cells are destroyed by oncolysis, they release new infectious virus particles or virions to help destroy the remaining tumor. Oncolytic viruses are thought not only to cause direct destruction of the tumor cells, but also to stimulate host anti-tumor immune system responses.

Source:

Clark, M., Douglas, M., Choi, J. Biology 2e. Houston, Texas: OpenStax. Access for free at: https://openstax.org/details/books/biology-2e

https://en.wikipedia.org/wiki/Receptor_(biochemistry)

https://en.wikipedia.org/wiki/Vaccine

https://en.wikipedia.org/wiki/Oncolytic_virus


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